سیدشاکر هاشمی

One of the main reasons for spur dikes destruction that are the major flood control and river training structures is the local scour around spur dike, especially in times of flood. Therefore the study of flow pattern and bed topography resulting from the construction of the spur dike and determining the depth of local scour around this structure plays an important role in the design of spur dike, in this way that the foundation of spur dike designed and implemented at the lower level of maximum local scour depth. This research is focused on the numerical calculations of scour and flow pattern at a 90 degree channel bend around a particular type of spur dike that is known to T-shape spur dike using appropriate software to analyze the scour and flow pattern (SSIIM model) and the influence of parameters such as the relative curvature of channel bend, submergence ratio of spur dike and the distance between the series of spur dikes in changes of scour and flow pattern were investigated that the results are as follows: The SSIIM model is able to provide the amount and appropriate range of maximum scour and sedimentation. The size and location of vortices vary with changes in distances between the spur dikes and the submergence ratio of spur dike. By increasing the relative curvature of channel from 2 to 4, the maximum amount of sedimentation and scour increased, the scour and flow patterns change, the dimensionless ratios of the separation and reattachment zone length to the outer bank length and also the maximum power of the secondary flow decrease. By increasing the density of bed sediments, the maximum amount of scour and sedimentation decreases.